U.S. patent number 4,872,890 [Application Number 07/270,022] was granted by the patent office on 1989-10-10 for multi-stage gas-entrained liquid separator.
This patent grant is currently assigned to Dollinger Corporation. Invention is credited to Clyde W. Hawley, Ned L. Lamprecht.
United States Patent |
4,872,890 |
Lamprecht , et al. |
October 10, 1989 |
Multi-stage gas-entrained liquid separator
Abstract
A multi-stage entrained liquid-gas separator includes a housing
divided into upper and lower chambers. The lower chamber is
provided with a tangential gas-liquid stream inlet into an annular
chamber in which the large entrained liquid drops are centrifugally
impinged upon the chamber wall and drained into a lower sump. From
the annular inlet chamber the gas-liquid stream is caused to
abruptly change direction and flow into a lower-pressure area of
the lower chamber for further releasing entrained droplets. From
this area the gas-liquid stream is made to flow into an inner
chamber provided within the lower chamber and communicating with
the upper chamber. A preseparator housed in the inner chamber
separates by impingement and coalescence liquid droplets still
entrained in the gas-liquid stream and drains the coalesced liquid
into an inner sump which in turn drains via a trap into the lower
sump. From the preseparator, the gas stream still containing liquid
microdroplets is conveyed upwardly into the upper chamber and
through a two-stage principal separator in the first, fine upstream
stage of which the entrained microdroplets are separated by
impingement and coalescence from the gas stream and drained to an
upper sump. In the second, downstream coarser stage of the
principal separator, separated liquid droplets emerging from the
upstream stage are prevented by impingement and drainage from
becoming re-entrained in the gas stream discharged to the
atmosphere via a gas outlet. An embodiment directed to separating
oil from gas turbine bearing sump vent air is disclosed.
Inventors: |
Lamprecht; Ned L. (Rocky River,
OH), Hawley; Clyde W. (Chester, VA) |
Assignee: |
Dollinger Corporation
(Richmond, VA)
|
Family
ID: |
23029568 |
Appl.
No.: |
07/270,022 |
Filed: |
November 14, 1988 |
Current U.S.
Class: |
55/323; 55/487;
55/337 |
Current CPC
Class: |
B01D
45/12 (20130101); B01D 50/002 (20130101) |
Current International
Class: |
B01D
45/12 (20060101); B01D 50/00 (20060101); B01D
046/02 () |
Field of
Search: |
;55/320-323,337,345,487 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Hart; Charles
Attorney, Agent or Firm: Fleit, Jacobson, Cohn, Price,
Holman & Stern
Claims
We claim:
1. A multi-stage gas-entrained liquid separator comprising:
housing means having a first chamber and a second chamber separated
by a partition and communicable with one another through a first
aperture in said partition, said first chamber having an annular
passage provided with a tangential gas inlet for admitting an inlet
gas-liquid stream in a tangential path thereinto and for imparting
centrifugal action upon large liquid droplets entrained in said
admitted gas-liquid stream to cause impingement of said entrained
large liquid droplets against said housing means, said annular
passage opening into said first chamber, said first chamber further
being provided with an inner chamber separated from said annular
passage and communicable therewith by a second aperture so
positioned relative said gas inlet and said annular passage as to
impart a change of direction to said admitted gas-liquid stream,
said inner chamber also communicating with said first aperture,
said second chamber having a gas outlet for discharging a gas
stream therefrom, said fisrt chamber, second chamber and inner
chambers each having a respective liquid sump at a lower portion
thereof;
drain means for draining the respective liquid sumps of the first
and second chambers;
means for draining the liquid sump of the inner chamber into the
liquid sump of the first chamber;
preseparator means provided in said inner chamber for separating by
impingement thereon liquid droplets from said gas-liquid stream and
for coalescing and draining said separated liquid into said inner
sump, and for conducting said gas-liquid stream through said first
aperture into said second chamber; and
two-stage principal separator means provided in said second housing
for separating by impingement and coalescence thereon liquid
microdroplets entrained in said gas-liquid stream admitted thereto
from said preseparator means and for preventing by impingement
re-entrainment of coalesced liquid droplets therefrom into a gas
stream discharged therefrom.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
This invention pertains to means for the separation of entrained
liquids, e.g. aerosols, from gases. By the term "entrained liquids"
is meant moisture droplets, oil droplets and the like which are
borne as discrete physical particles entrained in a gas as aerosols
therein, for example an oil fog.
Various types of apparatus for separating entrained liquids from a
gas stream are known in the prior art, directed to particular
"de-aeration" applications such as for removing/separating excess
entrained lubricating/cooling oil from the compressed air stream
output by an air compressor before the compressed air is supplied
to pneumatic machines, or for removing/separating moisture
particles from the inlet air stream of a marine gas turbine, or for
the separation and/or removal of entrained liquid microdroplets
from a process gas stream. Examples of various known gas-entrained
liquid separation devices are disclosed in U.S. Pat. Nos.
1,552,903; 2,432,130; 3,494,110; 3,548,569; 3,870,493; 4,086,070;
4,092,137; 4,158,449; 4,255,099; 4,300,918; 4,506,523; 4,548,569;
and 4,668,256, the disclosures of which are hereby incorporated by
reference hereinto.
As an adjunct to separating the entrained liquid aerosols from the
gas stream, it is often desirable that the separated liquid be
removed, e.g. for collection and/or reuse. Typically, it is
desirable for efficient separation that the liquid, once separated
from the gas stream, not be re-entrained as an aerosol in the flow
of the gas. As a further adjunct, it is often desirable to clean
the gas stream.
Other considerations involved in the separation of entrained
liquids from gas streams include the factors of separation
efficiency, gas flow velocity, permissible pressure drop, and
aerosol particulate size and type. These factors are typically
interrelated and may often be interdependent, with one or more
factors being critical or paramount and thus dictating the
particular priority of design considerations. However, because some
factors may conflict with others, the design considerations often
require compromises such that some aspects of performance must be
traded off in favor of others, and thus the performance is less
than ideal. Where many factors must be optimized, the separator
design can become complex and costly to implement.
The present invention is directed particularly, but by no means
exclusively, to the separation and removal of entrained oil
droplets ("oil fog") from an oil-laden air stream venting from a
sump bearing of a gas turbine. A significant concern in such an
application is compliance with regulations proscribing standards
governing the venting/emission of aerosols such as oil fog into the
atmosphere. By way of example, it is desired to prevent entrained
oil fog from being vented directly into the atmosphere. For
compliance with applicable governing standards, it thus becomes
desirable to remove sufficient oil fog from a vented oil-laden sump
bearing air stream to reduce the residual oil-in-air concentration
in the air stream vented to the atmosphere to below the "visible"
level, for example below 30 PPM (parts per million).
However, the provision of an apparatus directed to achieving such a
level of separation performance must necessarily take into
consideration also the factors of air flow volume and velocity,
temperature, and tolerable air stream pressure drop, as well as the
oil content in the vent air stream, which last factor may not be
predictable and which may vary considerably over time. Further,
some factors may vary considerably depending upon the turbine
operating conditions. Another consideration involves the fact that
the entrained oil fog may typically consist of many different sizes
of oil droplets.
By the present invention, an apparatus is provided for separating
and removing entrained oil droplets from a gas stream, which
apparatus includes a preseparator/separator combination which is
arranged in a housing means having in a lower part thereof an
annular inlet chamber means for admitting and subjecting an
entrained oil droplet-laden air stream to centrifugal action,
direction reversal and velocity change, for forcing the larger oil
droplets out of the air stream by centrifugal force acting thereon
and causing the larger oil droplets to impinge on an impingement
surface, and then coalescing the impinged oil droplets into a
liquid and draining off this separated oil to a sump in the lower
part of the housing means.
Then the air stream, still transporting entrained oil droplets, is
next conducted to pass through a preseparator means also arranged
in the lower part of the housing means and containing an
impingement and coalescence medium for causing impingement and
coalescence of the transported oil droplets. The preseparator also
includes means for collecting the coalesced oil and draining it to
the sump in the lower part of the housing means.
After passing through the preseparator means the air stream may
still contain residual oil microdroplets. The apparatus further
includes a principal separator means arranged in an upper part of
the housing means and communicating with the preseparator means.
The air stream exiting the preseparator means and still containing
residual microdroplets is conducted upward to pass through the
principal separator means. The principal separator means is of two
stage configuration and includes an upstream stage separator
element and downstream stage separator element. The upstream stage
separator element promotes coalescence of the residual
microdroplets into liquid. The downstream stage separator element
prevents, by impingement, the re-entrainment of any now relatively
large coalesced oil droplets which may emerge from the upstream
stage separator element, and also directs drainage of the coalesced
oil to a sump provided in the upper part of the housing means. The
air stream, now purged of entrained oil to an acceptable level, is
then conducted to flow from an outlet in the upper part of the
housing means to be released into the atmosphere.
The sumps in the lower and upper parts of the housing means are
provided with drains to be connected to a receiving sump for
receiving the separated liquid oil.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features of the invention will be more fully
described in the detailed description which follows, with reference
to the drawings, in which:
FIG. 1 is a front view, partly broken away, of an exemplary
embodiment of a gas-entrained liquid separator according to the
present invention;
FIG. 2 is a top view of the embodiment of FIG. 1;
FIG. 3 is a front sectional view of the lower part of the housing
means;
FIG. 4 is a top cross-sectional view of the lower part of the
housing means taken along line IV--IV in FIG. 3;
FIG. 5 is a front view in half section of the preseparator means
according to the invention; and
FIG. 6 is a front view in half section of the principal separator
means according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, an exemplary embodiment of a gas-entrained
liquid separator according to the invention includes a cylindrical
housing means 10 which has a cylindrical outer wall 11 closed by a
bottom end 12 and a top lid 14. Housing means 10 is internally
subdivided into upper and lower parts by a partition 16. As seen
more clearly in FIG. 3, partition 16 is provided centrally with an
aperture communicating an upper chamber 18 and a lower chamber 20
defined above and below partition 16, respectively.
Lower chamber 20 is divided by a depending cylindrical inner wall
22 into an annular outer chamber 24 and a cylindrical inner chamber
26. Wall 22 depends only partially from partition 16 into lower
chamber 20, and proximate the depending lower end of wall 22 the
inner chamber 20 is closed by a bottom wall 28. Bottom wall 28 is
centrally provided with an aperture 29 therethrough which is
bounded by an upstanding cylindrical wall 30 extending partly
upwardly above wall 28 and also depending partly downwardly from
wall 28. Aperture 29 thus communicates the outer chamber 24 and
inner chamber 26 of the lower chamber 20.
As shown in FIGS. 1-4, the housing means 10 is further provided
with a tangential inlet pipe 32 which passes through outer wall 11
proximate the top portion of lower chamber 20 and opens
tangentially into annular outer chamber 24 of lower chamber 20 for
admitting an oil-laden inlet air stream thereinto. Further, the
upper chamber 18 and lower chamber 20 are provided at their
respective bottom end portions with drains 34, 36, respectively,
communicating with the exterior of the housing means 10. Still
further, the housing means 10 is provided proximate the top end
thereof with an outlet pipe 38 communicating with the upper chamber
18 for the discharge of the air stream therefrom.
As may be seen from FIGS. 1 and 3, the lower chamber 20 is provided
with a number of downcomer pipes 40 depending downwardly from
bottom wall 28 of inner chamber 26. The lower ends of downcomer
pipes 40 are received in cup-like traps 42 in the lower portion of
lower chamber 20, the purpose of which will be explained below.
It should be noted that the junctures of the various walls and
surfaces are made gas and liquid tight. The closed bottom of the
lower chamber serves to provide a lower sump 44, the practical
liquid level in which is designated by the dashed line in FIG. 3,
and which may be drained via the drain 36. The annular bottom
portion of inner chamber 26 defined by walls 22, 28 and 30 serves
to form an inner sump 46, the practical liquid level in which is
designated by the dot-dash line in FIG. 3. As may be seen, the
downcomer pipes 40 drain the inner sump into the lower sump 44,
however, drainage from inner sump 46 into lower sump 44 is
regulated by traps 40 which are filled with oil, as will be more
fully explained below.
Referring now to FIGS. 1 and 5, there is shown the preseparator
means 100 according to the invention. In use, preseparator means
100 is arranged within the inner chamber 26 of lower chamber 20.
The preseparator means 100 includes a cylindrical preseparator
element 102 typically of homogeneous glass fiber media which is
convoluted to provide sufficient area for proper operation, and
having such a fiber size and density as to cause impingement and
coalescence of entrained oil droplets thereon and therein, while
still permitting uninhibited drainage of collected oil to the inner
sump, as will be more fully described below.
Preseparator means 100 further includes cylindrical inner and outer
support members 104, 106, typically of freely gas permeable open
screening, perforated or expanded material for rigidly supporting
the preseparator element 102, and annular channel section upper and
lower support flanges 108, 110 for rigidly supporting the inner and
outer support members 104, 106 and the preseparator element 102.
Lower support flange 110 is provided on its underside with an
annular gasket 112 for sealing against the bottom wall 28 of the
inner chamber 26. Preseparator element 102, support members 104,
106 and support flanges 108, 110 are sized such that the inner
diameter of preseparator means 100 fits with a slight clearance
around the throat of the upstanding cylindrical wall 30
communicating the inner chamber 26 with the lower chamber 20, with
the preseparator means 100 seated on bottom wall 28. Further, the
outer diameter of preseparator means 100 and the inner diameter of
cylindrical wall 22 are sized to allow a slight clearance
therebetween.
Extending upwardly from the upper support flange 108 there is
provided a cylindrical riser or flue 114 of rigid freely gas
permeable open screen or perforated or expanded material. Riser 114
is provided at its upper end with an annular flange 116 having a
collar portion 118 and a radially extending flange portion 120.
Riser 114 also is provided at its lower end with a support collar
122 which may be formed as part of the upper support flange 108. An
annular gasket 124 is provided on the underside of the flange
portion 120 of flange 116. The radial extent of flange portion 120
is greater than the outer diameter of the preseparator element 102,
support members 102, 104, and support flanges 108, 110. Further,
the radial extent of flange portion 120 is greater than the
diameter of the aperture 17 in the partition wall 16 dividing the
upper and lower chambers 18, 20, while the outer diameter of the
preseparator element 102, support members 104, 106 and support
flanges 108, 110 is smaller than the diameter of aperture 17. In
this way, the preseparator means 100 may be inserted into and
withdrawn from the inner chamber 26 from above through the aperture
17. The height of the preseparator means 100 from the gasket 112 to
the gasket 124 thus corresponds to the distance from the top
surface of partition 16 to the top surface of bottom wall 28.
Further, when the preseparator means 100 is seated in the inner
chamber, the the upstanding cylindrical collar portion 118 of
flange 114 extends above the partition wall 16 to a sufficient
extent to form an annular upper sump 48 in the lower end of the
upper housing, the practical liquid level of which is designated in
FIG. 3 by the dash-double dot line. Thus, the flange 116 of riser
114 prevents liquid collected in the upper sump 48 from flowing
down into the inner chamber 26.
In FIG. 6 there is shown the principal separator means 200 of the
invention. Principal separator means 200 is of two-stage design and
includes a cylindrical inner upstream stage separator element 202
and a cylindrical outer downstream stage separator element 204.
Upstream stage separator element 202 is preferably formed of a
special borosilicate glass fiber media formed into a convoluted
configuration to provide adequate flow area in a confined space.
The media micro fiber size and density are chosen such as to
promote coalescence of residual oil microdroplets in the air stream
into liquid. The downstream stage separator element 204 preferably
consists of coarser homogeneous glass fibers for preventing, by
impingement thereon, the re-entrainment of any coalesced oil
droplets that may emerge from the upstream stage separator element
202, and for directing drainage of the collected oil down to the
upper sump 48.
The upstream and downstream stage separator elements 202, 204 are
each supported by respective cylindrical freely gas-permeable inner
and outer support members 206, 208 and 210, 212, respectively, in
similar manner as the preseparator element 102. Further, the
elements 202, 204 may be mounted for being supported at their
respective upper and lower ends within upper and lower annular
channel-shaped rims 214, 216 respectively, as by potting sealant
218 or like means.
Upper and lower rims 214, 216 may conveniently be identical and are
each provided in the respective upper and lower central surfaces
thereof (as oriented in FIG. 6) with circular grooves 220 in which
are accommodated O-rings 222 whereby the lowermost rim (216 in FIG.
6) may be sealed down against the upper surface of the radial
flange portion 120 of flange 116 of the preseparator means 100 when
same is seated on the partition wall 16. Thus, the lower O-ring 222
cooperates with the gasket 124 of radial flange portion 120 to seal
the upper sump 48 against draining into the inner chamber 26.
The inner diameter of principal separator means 200 (i.e. of rims
214, 216) is preferably sized slightly smaller than the diameter of
aperture 17, but is preferably considerably larger than the outer
diameter of the upstanding collar portion 118 of the flange 114 of
preseparator means 100, while the outer diameter of the principal
separator means 200 is preferably the same as the outer diameter of
the radial flange portion 120 of the preseparator means 100.
Rods 224, which are threaded at least over their upper extent,
extend upwardly from the partition wall 16 and in spaced relation
around the periphery of principal separator means 200. A sealing
plate 226 may be clamped sealingly atop the upper O-ring 222 of the
upper support rim 214 by nuts 228 or the like fastened to rods 224
for mounting the principal separator means down onto the radial
flange portion 120 in the upper chamber 18, with the upper open end
of the principal separator means 200 being sealed closed by the
sealing plate 226.
Referring again to FIGS. 1-4, the oil-laden air stream, for example
vent air from a gas turbine bearing sump containing an entrained
oil fog, is conducted to tangential air stream inlet 32 by suitable
piping (not shown) and is admitted by inlet 32 into the upper
portion of the annular outer chamber 24, the air-oil stream
entering the upper annular space of chamber 24 tangentially as
shown by the arrows in FIG. 4. This tangential entrance imparts a
centrifugal action to the air-oil stream forcing the larger
entrained oil drops to impinge on the inner surface of wall 11,
coalesce into liquid, and drain into the lower sump 44.
As shown by the arrows in FIGS. 1 and 4, the air stream, still
transporting oil droplets, then passes downwardly into the lower
chamber 20 and enters a region of reduced flow velocity (i.e. an
enlarging volumetric flow path) and also makes an abrupt reversal
of flow direction dictated by the arrangement of the depending
inner wall 22 within lower chamber 20, which actions cause more oil
droplets to be released from the air-oil stream.
The air-oil stream then passes upwardly through aperture 29 and
into the inner chamber, and radially outwardly and upwardly through
preseparator means 100, as shown by the arrows in FIG. 1. In
passing through preseparator element 102, oil droplets in the
air-oil stream are caused to impinge and coalesce in and on the
element 102, and the coalesced oil drains through and over element
102 and down into inner sump 46 where it is collected. Because the
pressure within inner chamber 26 is lower than that in lower
chamber 20 due to the pressure drop through the preseparator
element 102, provision of traps 42 at the outlets of downcomer
pipes 40 prevents the oil collected in lower sump 44 from flowing
up into inner sump 46.
The air stream after passingly through the element 102 and still
containing residual entrained oil microdroplets, passes inwardly
and upwardly into and through the freely permeable riser 114 and is
conducted upwardly into the upper chamber 18 whereupon the air-oil
steam passes upwardly and radially outwardly through first the
upstream separator element 202 and then the downstream separator
element 204 of two-stage principal separator means 200. The
residual oil microdroplets are promoted to impinge on the fine
media of the upstream element 202 and to coalesce into liquid which
is drained into the upper sump 48. The upstream element, being
coarser, prevents by impingement the re-entrainment of the
coalesced and now relatively large oil droplets that may emerge
from the upstream element media, and also directs drainage of
impinged, coalesced and collected oil droplets to the upper sump
48.
After passing through the principal separator means 200, the air
stream, now purged of entrained oil to an acceptable level of
concentration, exits from the upper chamber via the outlet 38 and
into the atmosphere.
Testing has indicated that whatever arrangement of separator
element flow and oil scavenge is used, the successful operation of
the apparatus is dependent upon the ability of the scavenge or
drain to remove oil from the element sumps as rapidly as the oil is
collected. Element flow direction is not in itself critical, but
becomes so in the design of a practical system that can provide
adequate scavenging, and this factor applies equally to both the
preseparator and principal separator arrangements. The upper and
lower sump drains 34 and 36 must be connected to a receiving sump
(not shown) that is at a lower pressure than either of the upper
sump 48 and lower sump 44.
It will be appreciated that the aforedescribed invention is
amenable to various modifications and applications and is not to be
limited to the exemplary embodiment described and shown, but that
various modifications will fall within the scope of the appended
claim.
* * * * *